The present invention relates to a method and apparatus for detecting the presence of powdered materials in closed envelopes, in particular, for detecting powdered infectious, contagious, contaminating, or other undesired substances that can be sent via mail.
Recent increase in the acts of terrorism, in particular, of bio- and chemical terrorism, caused US Government to undertake development of new reliable and rapid-response measures for dealing with the suspicious substances in the mail, which appeared to be one of convenient channel for delivery of contagious bio- and chemical substances to governmental offices, companies, and individuals. One such measure is irradiation of mail started by the U.S. Postal Service in response to anthrax mail contamination that has been found on Capitol Hill, in White House Postal Service, in offices of senators, and in other locations. Contaminated mail has sickened more than a dozen people and claimed the lives of postal workers at some mail sorting centers.
PlasmaSol Corp., N.J., has developed xe2x80x9cnonthermal plasmaxe2x80x9d that emits germ-killing ultraviolet rays and creates ozone that oxidizes chemicals and bacteria like a disinfectant. This device can work under normal atmosphere and therefore do s not require the use of complicated and expensive vacuum and vacuum-sealing equipment. Tests on the anthrax-like bacteria have generated positive results. However, regular envelopes are not transparent, and thus high doses of ultraviolet irradiation are required, which limits its practical use.
Total irradiation of the entire mail circulating through the United States may be an unreal objective in view of its high cost and extremely small amount of contaminated mail as compared to millions of items circulating daily through the channels of the U.S. Postal Service. High radiation doses needed for decontamination of bacteriological particles require expensive protection of and highly qualified personnel working with this equipment at postal facilities. Also, maintenance of the mail irradiation equipment will be no less expensive than its operation.
In view of the sporadic and random distribution of contaminations mail, it would be more appropriate to conduct selective screening at the mail destination locations only of those letters and packages that seem suspicious. However, since the United States were taken with the acts of bio-terrorism by surprise, this country has not yet developed reliable equipment for the solution of the above problem.
In fact, some specialized biological agent detection devices existed in the civil defense system. For example, in 1994 the Department of Defense disclosed the existence of almost 40 Biological Integrated Detection Systems (BIDS) designed for Army. However, all these systems were intended for battlefield conditions and had not been introduced into practical use, due to no demand for such use. Nevertheless, at the present time BIDS uses off-the-shelf instrumentation, including an aerosol-particle counter/sizer, a bioluminescence analyzer, a liquid-particle counter/sizer, a particle sampler, and a manual antibody-based detector. Among the agents that BIDS is required to detect and identify are anthrax and plague bacteria, botulinal toxin A, and staphylococcal enterotoxin B.
In response to the recent anthrax menace, some commercial companies have developed and are selling on-site detection kits for anthrax, as fears of the often-lethal bacteria spread across the country. One example of such bacteria-detection equipment is Smart Cycler, produced by a private company Cepheid, California. This device combines optical spectroscopy with fluorescent analysis and makes it possible to detect anthrax and other hazardous biological substances.
Although the Smart Cycler operates reliably and efficiently, it is only a detection device, which requires a special procedure for preparation of test samples. Furthermore, this device, like any other detector, requires preliminary revealing of suspicious objects, e.g., closed postal envelopes with suspicious contents. It is well known that in majority of cases the biological contaminants comprise fine powders, which are convenient for delivery through mail and which immediately scatter in air when the envelope is opened. Thus, prior to detecting and defining the suspicious powder, it is necessary to reveal a suspicious envelope, to open it under conditions safe for the personnel, and to test the interior of the envelope for the presence of a powder, irrespective of whether this powder is contagious or neutral, and only in the case the powder is found, it is then detected and analyzed in such a device as Smart Cycler. However, at the present time none such equipment, suitable for use in facilities receiving from several to thousands letters per day, is available.
It is an object of the invention to provide a method and apparatus for revealing mail with suspicious contents as a measure of preliminary presorting of closed postal envelopes and for making the mail with suspicious substances available for a further detailed analysis. It is another object to provide the aforementioned apparatus, which is simple in construction, inexpensive to manufacture, simple and safe in use, and incorporates a commercially produced particle detector. It is another object of the invention to provide the aforementioned apparatus, which is equipped with an electronic control unit that controls operation of a cutter, envelope excitation means, alarm and locking devices. It is another object to provide the aforementioned apparatus and method suitable for use in mailrooms of enterprises, companies and establishments that daily receive from several to thousands items of mail.
An apparatus of the invention for detecting the presence of powdered materials in closed envelopes comprises a sealed container provided with a loading/unloading port, an envelope-positioning unit, envelope corner or edge cutter, a powder excitation and extraction unit for exciting the contents of the envelope, and a powder detector with a particle intake device, and an air circulation system for circulation of the particle-containing air through the powder detector. The detector can be placed inside or outside of the sealed container and is connected to the cutting zone via the particle suction device. In operation, each piece of the selected suspicious mail is placed into the envelope-positioning unit that can be located inside the container, e.g., on the backside of the door, so that either a corner or an edge of the envelope is aligned with the position of the cutter. The door is closed for sealing the container with the envelope to be tested. The corner or the narrow edge of the envelope is cut off or perforated so as to allow the powdered material to come out from the envelope while maintaining the other contents, except for small particulates, intact and inside the envelope. The envelope is then subjected to either vibrations or impacts under the effect of the excitation and extraction device. If the envelope contains any fine powdered material, the vibrations will excite the fine powdered particles, which begin to move. This will cause the powder to leave the envelope through the opening formed in the cut-off corner or edge perforations of the envelope. The particles suspended in air underneath the envelope corner will be sucked into the particle intake device and delivered to the powder detector. The results of particle analysis can be displayed or recorded, as well as analyzed by a control unit, while the air exhausted from the powder detector will return to the container and will circulate through the above-described path. The judgment on the presence of the suspicious substance will be made by comparing the measured data with a predetermined reference threshold. The maximum threshold value for the number of particles unloaded from a single envelope is selected based on real conditions, according to which the detector will produce an alarm signal if the number of particles will exceed the predetermined threshold. In case of detection of a hazardous material, the apparatus will produce both sound and visible alarm signals, at the same time locking the door to prevent access to the apparatus for unauthorized personnel.